Arthropathy is a joint disease induced by various diseases. Among various types of arthropathy, numbers of patients suffering from osteoarthritis (OA) and chronic rheumatoid arthritis (RA) are particularly large and those have been believed to be the main arthropathy. When degeneration and abrasion of cartilage are resulted in osteoarthritis due to some causes such as mechanical stimulation, they grow as abnormal cartilage and osteophyte on the surrounding site suffering from no burden during the repairing process whereupon deformation of a joint proceeds. As a result of such a change, synovial membrane in the joint is inflamed and abnormally grows whereupon water is accumulated in the joint. As to the osteoarthritis, osteoarthritis of knee and osteoarthritis of hip have been well known. Further, in chronic rheumatoid arthritis, non-specific inflammation is induced in synovial membrane in the joint resulting in pain and swelling accompanied by proliferation of synovial cells whereupon joint fluid increases and destruction of cartilage and bone proceeds. With regard to the therapy of osteoarthritis and chronic rheumatoid arthritis, mechanism of onset and progress thereof has not been completely clarified yet whereby radical therapy for eliminating the causes is unable to be expected at present and, in addition, no therapeutic method for regenerating the abraded cartilage and the deformed joint to the original state has been established yet. Accordingly, a conservative therapy by means of exercise therapy, physical therapy, pharmaceutical agent therapy, etc. for relieving the pain and the symptom and not for further worsening the state of disease is a fundamental means. In view of the current situations as mentioned above, there has been a strong demand from the clinical site for drugs exhibiting excellent effect to arthropathy such as osteoarthritis and chronic rheumatoid arthritis.
The present inventors have found that the coumarin derivative of the present invention is useful as a pharmaceutical agent such as a preventive or therapeutic agent for arthropathy since it exhibits a suppressive action for the destruction of cartilage and a suppressive action for the proliferation of synovial cells. With regard to a coumarin derivative, a compound where sulfonylamino is substituted at 3-position of a coumarin skeleton is disclosed in Non-Patent Documents 1 and 2 but those documents merely report that such a compound is synthesized and do not mention at all that the compound exhibits a pharmacological action.